Diabetes mellitus includes a cluster of diseases distinguished by chronic hyperglycemia that result from the body's failure to produce and/or use insulin, a hormone produced by β-cells in the pancreas that plays a vital role in metabolism. Symptoms include increased thirst and urination, hunger, weight loss, chronic infections, slow wound healing, fatigue, and blurred vision. Diabetes can also comprise abnormalities of carbohydrate, fat, and protein metabolism attributed to the deficient action of insulin on target tissues resulting from insulin insensitivity or lack of insulin.
Type 2 diabetes is the most common form of diabetes, which typically develops as a result of a relative, rather than absolute, insulin deficiency, in combination with the body's failure to use insulin properly (also known in the art as “insulin resistance”). Type 2 diabetes often manifests in persons, including children, who are overweight. Other risk factors include high cholesterol, high blood pressure, ethnicity, and genetic factors, such as a family history of diabetes. The majority of patients with type 2 diabetes are obese, and obesity itself may cause or aggravate insulin resistance.
Gastroparesis is a condition characterized by delayed gastric emptying and associated upper gastrointestinal (GI) symptoms. Paresis of the stomach causes food to remain in the stomach for a longer period of time than normal. Diabetic gastroparesis affects many patients who suffer from diabetes.
U.S. Pat. No. 6,600,953 to Flesler et al., which is incorporated herein by reference, describes apparatus for treating a condition such as obesity. The apparatus includes a set of one or more electrodes, which are adapted to be applied to one or more respective sites in a vicinity of a body of a stomach of a patient. A control unit is adapted to drive the electrode set to apply to the body of the stomach a signal, configured such that application thereof increases a level of contraction of muscle tissue of the body of the stomach, and decreases a cross-sectional area of a portion of the body of the stomach for a substantially continuous period greater than about 3 seconds.
PCT Patent Publication WO 99/03533 to Ben-Haim et al., entitled, “Smooth muscle controller,” and U.S. patent application Ser. No. 09/481,253 in the national phase thereof, both of which are incorporated herein by reference, describe apparatus and methods for applying signals to smooth muscle so as to modify the behavior thereof. In particular, apparatus for controlling the stomach is described in which a controller applies an electrical field to electrodes on the stomach wall so as to modify the reaction of muscle tissue therein to an activation signal, while not generating a propagating action potential in the tissue.
U.S. Pat. No. 6,571,127 to Ben-Haim et al., which is incorporated herein by reference, describes methods of increasing contractile force and/or the motility of a GI tract. A first method comprises selecting a portion of the GI tract and applying a non-excitatory electric field to the portion, which field increases the force of contraction at the portion.
Sanmiguel C P et al., in an article entitled, “Gastric Electrical Stimulation with the TANTALUS® System in Obese Type 2 Diabetes Patients: Effect on Weight and Glycemic Control,” J Diabetes Sci Technol 3(4):964-970 (July 2009), which is incorporated herein by reference, describes gastric electrical stimulation (GES) using the TANTALUS® System, which consists of an implantable pulse generator connected to gastric electrodes. The system is designed to automatically detect when eating starts and only then deliver sessions of gastric electrical stimulation (GES) with electrical pulses that are synchronized to the intrinsic antral slow waves. The authors report the effect of this type of GES on weight loss and glucose control in fourteen overweight/obese subjects with type 2 diabetes mellitus (T2DM), on oral antidiabetes medication. Gastric electrical stimulation was initiated four weeks after implantation. Weight, HbAlc, fasting blood glucose, blood pressure, and lipid levels were assessed during the study period. Eleven subjects reached the 6-month treatment period endpoint. Gastric electrical stimulation was well tolerated by all subjects. In those patients completing 6 months of therapy, HbAlc was reduced significantly from 8.5±0.7% to 7.6±1%, p<0.01. Weight was also significantly reduced from 107.7±21.1 to 102.4±20.5 kg, p<0.01. The improvement in glucose control did not correlate with weight loss (R2=0.05, p=0.44). A significant improvement was noted in blood pressure, triglycerides, and cholesterol (low-density lipoprotein only). The authors conclude that short-term therapy with the TANTALUS System improves glucose control, induces weight loss, and improves blood pressure and lipids in obese T2DM subjects on oral antidiabetes therapy.
Sanmiguel C P et al., in an article entitled, “The TANTALUS™ System for obesity: effect on gastric emptying of solids and ghrelin plasma levels,” Obesity Surgery 17:1503-1509 (2007), which is incorporated herein by reference, describes gastric electrical stimulation, using the implantable TANTALUS System, as a treatment for obesity. The system is described as delivering nonstimulatory electrical signals synchronized with gastric slow waves, resulting in stronger contractions. The study tested the effect of GES on gastric emptying of solids and on ghrelin and insulin blood levels in obese subjects.
UltraFlex Implantable Gastric Lead data sheet (MetaCure (USA), Orangeburg, N.Y.), which is incorporated herein by reference, provides information regarding this lead.
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